In modern cargo carrying aircraft, cargo may be loaded through a cargo door located in a side of the fuselage. Cargo is normally packaged either in specially designed containers or on pallets. Both are known as unit load devices (ULDs). Passenger luggage is typically stowed in a container, while bulk freight, such as dry goods, is usually stowed on pallets. Typically, containers measure 60.4 inches in length and pallets are either 88 or 96 inches long. The ULD is then transferred into the fuselage through the cargo door and is maneuvered within the fuselage on the cargo deck. The cargo deck typically has a plurality of omni-directional and directional transfer supports to ease the passage of ULDs over the deck and into a final stowed positioned where it is secured to the cargo deck by a number of either fixed or relocatable restraints.
Airline operators frequently transport a mixture of containers and pallets. Current loading procedures on certain wide body airplanes require repeated loading of containers without restraints placed between the containers, and is known in the art as gang or stack loading. Pallets are individually restrained (i.e., pallet locks are raised after loading each pallet). Individually restraining ULDs is more time consuming than gang loading. Ideally, pallets are loaded into the fuselage first, such that they are located furthest from the cargo door. Loading pallets first is desirable because containers typically contain passenger luggage and should be unloaded first to facilitate expedient transfer of the luggage to its final destination. After each pallet is loaded, pallet lock restraints, located adjacent the base of the pallet, are locked into an upright position and prevent the pallets from moving longitudinally within the fuselage. If the operator desires to load containers after the pallets have been loaded, an end stop could be placed in the cargo deck between the last pallet and first container or the last pallet lock may be used. Finally, after the last container has been loaded, another set of restraints is locked into position to prevent longitudinal movement within the fuselage during operation of the aircraft.
Cargo restraints currently available have several aspects that detract from their usefulness. Typical restraints available in the art restrain movement of the containers in only one direction, and therefore, both load and end stops are required when carrying a mixture of containers and pallets. Also, because the lengths of the containers and pallets are not multiples of each other, intermixing both containers and pallets require either a large number of fixed restraints or the restraints must be easily relocatable to accommodate the large number of potential container/pallet combinations. Additional restraints add more weight to the aircraft and, therefore, reduce the amount of revenue generating weight that the aircraft can carry. Relocatable restraints are required to be positioned within the cargo deck before the cargo hold is loaded to accommodate the planned mix of containers and pallets, thereby requiring additional time on the ground. In an industry where time is of the essence, any additional time required to ensure proper location of the restraint system is undesirable. Furthermore, if the restraints are relocatable, they may be lost, stolen or mislocated causing damage to the aircraft. Finally, if the relocatable restraints are retained in some type of track, the restraints eventually become difficult to slide along the track because of damage or a build up of debris.
Thus, there exists a need for a cargo restraint that reduces the chance of being lost or stolen, and that can be permanently located to readily accommodate an intermix of containers and pallets. The present invention addresses these and other issues in overcoming the limitations currently encountered in the art.